Unfit to fly, any carrier
If an obviously bladdered or hyped (drugs or other) person is putting other pax ill at ease, it is the pax's right to notify the carrier's staff and/or agents of the concerns prior to bording. This is a flight safety issue, and you can, and should report this to the CAA (UK operators). For Easy, country of acft reg, i.e. in GVA the Swiss. Last resort is to use the "hated" media. Yes I have denied boarding to Co. acft at many locations. If you have a phone with video capture, use it as evidence, and tell the carrier's staff/agents you have. We don't want these folks on our acft any more than you do, as you'll not come back as a repeat customer. Third party ground handling agents tend not to be that concerned!